我們已經研究金屬-氧化物-高介電係數介電層-氧化物-矽結構(MOHOS-type flash memory) 並使用HfO2 和Dy2O3 作為高介電係數介電層結構的電容器和電晶體。並對元件作基本的電性量測與可靠度分析；首先藉由不同的儲存層材料的差異，探討其對MOHOS元件電特性的影響；再來探討不同RTA溫度對儲存層特性的影響。
由MOHOS電容結構的量測結果，在J-V curve的測量上，使用HfO2當作電荷儲存層的樣品在10V的外加電壓下RTA 600℃時有最小的漏電流密度大小為10-6 A/cm2；而使用Dy2O3當作電荷儲存層的樣品在10V的外加電壓下RTA 400℃有最小的漏電流大小密度為10-8 A/cm2。
由MOHOS電晶體結構的結果，在基本電性上的表現，如：ID-VD，ID-VG及C-V等，皆證明電晶體能夠正常的操作，使用Dy2O3材料當作電荷儲存層的樣品，在基本電晶體電性方面其次臨界斜率為St=104.2 mV/dec、遷移率為276 cm2/V-sec，在記憶體特性方面其寫入速度為+12V經過10 ms能夠有1.1V的Vth差、I-V memory window大小為1.85V、retention time為2x108秒(6年)。

Abstract

Conventional SONOS (polysilicon-oxide-nitride-oxide-silicon) non-volatile memory devices use silicon nitride as the charge storage layer. In this work, metal–oxide–high-k dielectric–oxide–silicon (MOHOS) capacitors and transistors are fabricated using HfO2 and Dy2O3 high-k dielectrics as the charge storage layer. The Al/SiO2/Dy2O3/SiO2/Si capacitors have a C-V memory window of 1.88V. The leakage current density of the Al/SiO2/Dy2O3/SiO2/Si capacitor is 10-8A/cm2 at 10V. The leakage current density of the Al/SiO2/HfO2/SiO2/Si capacitor is 10-6/cm2 at 10V. The leakage current density of the Al/SiO2/Dy2O3/SiO2/Si capacitor is lower than that of Al/SiO2/HfO2/SiO2/Si capacitor at the same bias voltage.
The programming speed of Al/SiO2/Dy2O3/SiO2/Si transistor is characterized by a Vth shift of 1.1V with a programming stress pulse voltage of 12V for 10 ms. After a +12V, 0.1 s program pulse and a -12V, 0.5 s erase pulse, the Al/SiO2/Dy2O3/SiO2/Si transistors can keep a ΔVth window of 0.5V for 2x108 seconds. The corresponding numbers for Al/SiO2/HfO2/SiO2/Si transistors are 100 ms and 2x104 seconds. The better performance of the Al/SiO2/Dy2O3/SiO2/Si transistors is attributed to the larger conduction band offset at the Dy2O3/SiO2 interface (2.3eV) versus 1.6eV at the HfO2/SiO2 interface.

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